Apparatus for the treatment of paper stock



Oct. 16, 1962 H. BIDWELL APPARATUS FOR THE TREATMENT OF PAPER STOCK Filed May 5, 1960 /NVENTOR HOWARD .B/DWELL BY fi United States Patent 3,058,678 APPARATUS FQR THE TREATMENT OF PAPER STOCK Howard Bidwell, Granby, Mass, assignor of one-half to Rachel Bidwell, Granby, Mass. Filed May 3, 1960, Ser. No. 26,527 4 Claims. (Cl. 241-260) This invention relates to improvements in methods and apparatus for separating fibres from paper stock aggregate and the fibrillation of the separated fibres by means of the combing action of granular surfaces or edges over or between which the stock to be treated is caused to flow.

This application is a continuation in part of my copending application Serial No. 551,845, filed December 8, 1955, now matured into Patent No. 2,936,128 of May 10, 1960.

In general, apparatus of the above type comprises or includes an annular stator within which a rotor is mounted and driven in spaced relation to the inner wall of the stator. The surface of the stator and rotor are provided with overall granular surfaces. Stock is fed to the center of the upper face of the rotor through an opening in the stator above the rotor and is driven by centrifugal force .to the periphery of the rotor whence it in part passes downwardly between the rotor and stator and in part returns to the center of the upper surface of the rotor. The working surfaces of the stator and rotor are variously contoured and tooled to control the direction and character of the flow of the stock over and against the granular surfaces of the stator and rotor, all as fully taught and described in said copending application and my prior Patent No. 2,912,174, issued November 10, 1959.

It has been found advantageous in many cases to recirculate the stock in whole or in part through same, or other, apparatus. It has also been found that the pressure under which the moving stock engages the granular surfaces affects the degree and character of the treatment of the fibre aggregate, and that control of these pressures is important in the treatment of the aggregate in its various stages of fibre separation and fibrillation and in the treatment of fibres of differing character. It has further been found that pressurizing the stock increases the friction between the fibres effecting a further fibre separation and fibrillation of the fibres.

It is the principal object of the present invention to provide ways and means for controlling the pressure with which the stock engages the granular surfaced members of the apparatus and further to provide means for establishing differential pressures or pressure potentials in the stock at predetermined locations in the general path of stock fiow, whereby removal of a portion of the partially treated stock from the flowing mass, for the purpose of recirculation through the same or other apparatus is facilitated, and in general to control and vary the overall pressure conditions in the stock in its passage through the apparatus, whereby more efficient, uniform and more complete fibre separation and fibrillation is effected. A further object is to prolong the time in which the stock is subjected to the processing action, both as regards con tact with the abrasive surfaces and frictional engagement of the fibres and aggregate particles.

Other and further objects and advantages of the invention will be made apparent in the following specification and claims. a

In the accompanying drawing:

FIG. 1 is a side view, partly in section and with parts broken away, showing a stator and rotor combination embodying the invention; and

FIG. 2 is a similar view of a rotor and stator combina- 3,58,678 Patented Oct. 16, 1962 tion embodying the invention in an alternative or modified form.

Referring to FIG. 1, which discloses a general combination more particularly intended for treatment of rag aggregate, the stator is shown as comprising body sections generally indicated at l and 2, and a cover section indicated at 3. A rotor, indicated at 4, is mounted for rota.- tion within the stator. The stator and rotor are mounted and the rotor driven by any suitable means, not shown, suitable means for these purposes being shown in the above identified copending application. The upper surface of the rotor, as shown, is provided with generally radial contours 5. The stock is fed to the center of the rotor through an opening 6 in the cover portion of the stator. The cover portion of the stator is also contoured, as indicated at 7, to affect the flow and treatment of a portion of the stock from the periphery of the rotor to the stator and back to the rotor. A portion of the stock in which the fibres have been fully or more completely separated passes over the peripheral edge of the rotor and flows down through the passage, generally indicated at 3, between the peripheral surface of the rotor and the opposing surface of the stator for discharge at the bottom. The opposed peripheral surfaces of the stato and rotor are provided with suitable contouring to effect further separation and fibrillation of the fibres, as indicated at 9 and 10, respectively. The surface contouring shown is in general conformity to that shown in my said copending application, but it will be understood that the surfaces may be variously contoured to meet the requirements of various types of stock. The walls of the rotor and opposing portion of the stator are generally cylindrical, the opposed lower portions 13 and 14 of the stator and 15 and 16 of the rotor being stepped laterally inward with respect to the opposed upper portions 11 and 12 of the stator and rotor, respectively, thus reducing the volume of that portion of the annular passage 8 below the center portion of the rotor. As is set forth in my copending application, the increasing decrease in the volume of such an inward stepping of passage 8 builds up a resistance to the flow, thus increasing the pressure with which the flowing stock is brought into contact with the abrasive surfaces and creating an increase in the fibre separating and fibrillating friction between the aggregate particles.

-In the combination disclosed in FIG. 1 this method of imposing pressure, in addition to the advantages it has in its pressurizing eifects on the stock, is employed to provide a differential pressure between the upper portion of the rotor and stator and the lower stepped portions thereof. The stator is provided with one or more openings, one of such openings being shown at 17 at the point where the differential pressure becomes effective. This pressure differential forces the stock through the opening 17 from which it may be carried by suitable conduits, not shown, back to the opening 6 of the cover of the stator or may be conducted to other processing means.

In FIG. 2 which discloses a general combination more particularly adapted for treating chemical pulps, alternative means are shown by which diiferential pressure intermediate the top and bottom of the rotor-stator combination may be effected. As shown in FIG. 2 the stator comprises a cover section 20, an upper section 21, and a lower section 22, while the rotor comprises an upper section 23 and a lower section 24. The top of section 23 of the rotor is provided with radial contouring 25, of any suitable form, which drives and directs the stock to the periphery of the rotor, where it in part passes downwardly through annular passage 26 discharging at the bottom, and in part impinges against the side walls of the stator section 20 to be treated and directed back to the center of the rotor by suitable contouring as indicated at 2.8.

In the form shown in FIG. 2, the peripheral surface of the upper portion 23 of the rotor and upper portion 21 of the stator are provided with similar channels or contours 30 which are inclined in directions such that rotation of the rotor enhances the advance of the stock along the channel 26 while the lower portions of the rotor and stator are provided with similar channels or contours 31 which are inclined in reverse directions to those of the upper portion of the rotor and stator to thereby retard the flow of stock through the lower portion of the channel 26. As a result of these differential pressures, pressure is built up between the upper and lower portions of the rotor which effects discharge stock through one or more openings 32 for recirculation through the device or introduction to other apparatus, as above described. The rotor and stator may be provided with other processing contours as indicated at 33.

In FIG. 2 the rotor sections 23 and 24 are shown supported on metal discs 35 but it will be understood that the sections may be integral as in FIG. 1, or otherwise connected in any suitable manner.

By varying the relative axial dimension of the portions of the rotor and stator above the discharge opening, in either form, it will be seen that the point at which the stock is removed from the stock flow, for recirculating or other treatment, may be varied, which in any given installation will determine the degree of processing to which the removed stock has been subjected as may be desired in over-all processing procedure.

It will be understood that in the form shown in FIG. 1 the reduction in the capacity of the lower portion of annular passage 3 is not limited to the right angle stepping there shown-the desired reduction in capacity can be secured by beveled steps or by making the surfaces of lower portions or sections of the stator and rotor frustroconical. The processing contours of the members such as are indicated at 5, 7, and 9 of FIG. 1 and at 28 and 33 in FIG. 2, may take various forms depending on the nature of the stock or type of processing which they are designed to accomplish and they may be formed to meet both processing requirements as well as to create pressure potentials, as for example by inclining the processing contours to impart advancing or retarding force to the stock or by substituting or adding contours inclined in accordance with the teaching of FIG. 2.

The broad concept of creating varying or opposed pressure potentials in the flow path of the stock by the character of the contouring, either dimensional, as in FIG. 1, or, in form or direction as in FIG. 2, or by combination of dimension, direction and form has a wide utility. While as above suggested it has advantages in facilitating recircling or otherwise further processing a portion of the stock it is not limited to such function or purpose.

As above pointed out the creation of pressure differentials in the fiow has been found advantageous in furtherance of the processing of the stock. The contouring of the granular surfaces, that is the channeling, recessing or striating of the opposing surfaces of the stator and rotor, or other stationary and relatively moving members to variously agitate, comb and manipulate the aggregate to eifect non-destructive separation of the fibres and fibril lation of the latter as the stock flows over and between the members, may take various forms and must take into account the nature and physical character of the aggregate.

For some processing purposes alternating compression and release, increasing or decreasing degrees of agitation, or variation in friction are desirable for different aggregates or at different stages of processing a given aggregate. Heavy processing may act to retard flow, while light processing may not retard flow and yet it may be desirable to retard the flow over contours which are light processing in character as where substantial fibre separation has been accomplished and fibrillation of the 4 fibres is the objective and the length of time of processing rather than its severity is desired.

By the present invention the most favorable pressure conditions may be established for the various stages of processing without sacrificing the efiiciency of the processing at any given stage. Further it provides variable control within limits for a given piece of equipment whose processing characteristics are fixed by the character of the processing contours of its members. The stock being processed is a fluid and transmits pressure in accordance with the law of hydraulics but it is a fluid changing in flow characteristics as the aggregate is broken up and becomes more uniformly difused. To give one example it may be found desirable by means such as shown in either FIGS. 1 or 2 to create a potential for creating resistance or back pressure at the lower portion of the device in excess of a desired minimum and maintain the pressure in the lower half at a desired figure below the potential maximum by removing a sufficient quantity of stock at openings such as 17 or 32 which may be controlled by any suitable manually set or pressure responsive valve.

In any event the present invention makes possible, in a fixed or variable manner, control over the pressure characteristics of the stock flow to permit the use of the most efiicient contouring for processing needs.

What is claimed is:

1. Apparatus for separating the fibres from waterborne paper stock aggregate and fibrillating the separated fibres which comprises a granular surfaced rotor, the granular surface including a substantially cylindrical peripheral surface and a circular upper end surface, an annular granular surfaced stator surrounding said rotor and spaced therefrom, said stator having a portion extending above the rotor and contoured to direct a portion of the stock discharged from the periphery of the upper end surface of the rotor freely back to the center portion of the rotor, the opposed surfaces of the upper portion of the cylindrical surface of the rotor and stator being respectively contoured to drive the remaining portion of the stock downwardly therebetween, the opposed surfaces of the lower cylindrical portion of the rotor and stator being respectively contoured to oppose the flow of stock therebetween to create pressure in the stock flowing in the passage between the rotor and stator at a zone intermediate the entrance and exit ends of said passage.

2. Apparatus as in claim 1, the stator being provided with an opening at said. zone to permit discharge of a portion of the stock from said zone.

3. Apparatus as in claim 1 the contours in the upper portion of the peripheral surface of the rotor and in the opposed surface portion of the stator comprising grooves inclined in the same direction, the contours in the lower portion of the peripheral surface of the rotor and the opposed surface of the stator comprising grooves inclined in opposite directions.

4. Apparatus as in claim 3, the stator being provided with an opening intermediate the said upper and lower portions of the rotor to permit discharge of a portion of the stock from said zone.

References Cited in the file of this patent UNITED STATES PATENTS 221,992 Allen Nov. 25, 1879 650,344 Zimmerman May 22, 1900 668,252 Beall Feb. 19, 1901 950,972 Walker Mar. 1, 1910 1,159,138 Vecchini Nov. 2, 1915 1,486,352 Manson Mar. 11, 1924 1,560,743 Van Buskirk Nov. 10, 1925 1,961,862 Park June 5, 1934 (Other references on following page) UNITED STATES PATENTS Tolman Jan. 15, 1935 Finnegan June 14, 1938 Keating Apr. 16, 1940 White Nov. 16, 1954 Shurts Oct. 28, 1958 Robertson Apr. 26, 1960 6 FOREIGN PATENTS Norway July 24, 1944 France Mar. 24, 1928 Germany July 26, 1954 France Mar. 26, 1952 

